There are so-called stepping excavators which are capable of some degree of rolling travel and are adapted to be laterally or longitudinally stepped with a striding movement. Such vehicles have been found to be particularly effective in sloping terrain and wherever there may be difficulty in assuring an effective purchase of the working platform upon the ground.
As a rule, such excavators have two wheel legs and two support legs. The wheel legs carry non-driven wheels while the support legs are provided with ground-engaging pads.
For a stepwise movement of the vehicle, the excavating boom or arm is drawn inwardly so that the shovel or scoop rests upon the ground, the support legs are raised and the vehicle body shifted using the rolling movement of the wheel legs; the support legs are then lowered to engage the ground, the scoop is raised and the process repeated for further advance of the excavator.
Such machines are not capable of self-propelled or purely rolling travel nor are they capable of a stepwise displacement without the aid of the excavator boom. As a result, the displacement in operation of the machine is inconvenient and unsatisfactory in many cases.